Tissue irrigating solution

ABSTRACT

In a tissue irrigating solution of the type containing the combination of glutathione, bicarbonate, and Ringer solution (GBR), the bicarbonate and glutathione are freeze-dried, packaged and separately stored in lyophilized powder form until just preceding the operation, at which time the lyophilized powder containing the bicarbonate and glutathione is dissolved directly into a conventional I.V. solution.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of my copending applicationSer. No. 07/577,306, filed Sep. 4, 1990 (now U.S. Pat. No. 5,104,663,issued Apr. 14, 1992) which, in turn, was a divisional of Ser. No.243,085, filed Sept. 9, 1988 and issued as U.S. Pat. No. 4,975,419 onDec. 4, 1990.

FIELD OF THE INVENTION

The present invention is directed to tissue irrigating solutions and,more particularly, to improved techniques for formulating and packagingthe components of a tissue irrigating solution containing glutathione,bicarbonate, and Ringer solution.

BACKGROUND OF THE INVENTION

During surgical procedures, it is important to minimize disturbance ofthe environment of tissue and cells as much as possible. A traumaticchange in the environment surrounding internal cells may, for example,lead to the destruction of such cells or the destruction of the functionof such cells. The destruction of cell function may even lead todestruction of other cells which are dependent upon a proper functioningof the destroyed cells. Therefore, during surgical procedures such as,for example, intraocular surgery, it is very important that the exposedtissue be continuously irrigated with solutions which approximatenatural body fluids. Such solutions are called "tissue irrigatingsolutions". One of the earliest tissue irrigating solutions forophthalmic procedures was an isotonic saline. However, it was quicklyrecognized that the isotonic saline was not adequate as an ophthalmicirrigating solution because it resulted in endothelial cell swelling,cell damage, and consequent corneal clouding.

Alternatively, various electrolyte solutions have been proposed astissue irrigating solutions, particularly in ophthalmic procedures,because such solutions more closely resemble the aqueous humor of theeye. The earliest electrolyte solution was known as Ringer's solution,which was a combination of sodium, calcium and potassium ions along withsodium lactate. Another solution intended for tissue irrigation is knownas a balanced salt solution (referred to as "BSS") which contains theessential sodium, potassium, calcium, and magnesium salt ions along withan acetate-citrate buffer system. It was successful and was used almostexclusively until several years ago. Within the last 10-15 years, therehas developed a tissue irrigating solution which is a combination of theRinger solution along with glutathione and sodium bicarbonate. This issometimes referred to GBR, and in recent years has become a recognizedtissue irrigating solution, especially for ophthalmic procedures. Whendextrose, sodium hydrogen phosphate (Na₂ HPO₄), and sometimes adenosineare added to GBR, there results a fortified or enhanced balanced saltsolution (sometimes referred to as "BSS Plus"), which has heretoforeproven to be very effective for intraocular surgery.

The problem with GBR solutions and particularly the fortified orenhanced balanced salt solution is that they do not exhibit long termstability. Because they must be mixed essentially at the operative site,it is difficult to control and maintain sterility. There are variousreasons why GBR type solutions are not stable. First, bicarbonate andphosphate tend to precipitate in the presence of the magnesium andcalcium ions. Therefore, once mixed, the sodium bicarbonate quicklyloses its ability to act as a pumping agent for causing the endotheliumto perform its fluid transport function of maintaining an outward fluidtransport to the stromal layer, which results in damage to the cornea.Stated otherwise, the purpose of the bicarbonate is to act as a pumpand, when mixed with the magnesium or calcium ions, it quickly loses itspumping action. A second reason why the GBR solutions are not stable isthat bicarbonate decomposes at a pH of less than about 8 and becomescarbon dioxide which again causes the bicarbonate to fail to act as achemical pump during the surgical procedure. Finally, the glutathione isunstable at a pH greater than about 5. Therefore, the glutathione cannotexist in a basic solution and the bicarbonate cannot exist for extendedperiods in an acid solution.

A solution to this problem has been offered in U.S. Pat. Nos. 4,443,432and 4,550,022, both issued to Garabedian et al. According to these twopatents, initially two solutions are prepared, a first, basic solutionproviding the bicarbonate and sodium phosphate, and a second, acidicsolution which provides the calcium and magnesium ions, as well as thedextrose and glutathione. The solutions are packaged and storedseparately and mixed within 24 hours of use.

While the resulting irrigating product as described the Garabedian et altechnique has achieved some degree of acceptance and success, there aresome limitations as a result thereof. First, the long-term stability andmaintenance of acceptable pH values is difficult to achieve inaccordance with the method and techniques described in the Garabedian etal patents. Second, in order to steam sterilize the first, basicsolution, it is necessary to place the glutathione in the second, acidicpackage, because glutathione cannot stand steam sterilizing. Third,since the sodium bicarbonate is in the first package, the package mustbe glass which is subject to breakage, because it is difficult tomaintain the stability of sodium bicarbonate in solution in a polymericcontainer. This occurs because sodium bicarbonate will not remain stablein a polypropylene bottle as a result of the transmission of vaporsthrough the wall of the bottle.

SUMMARY OF THE PRESENT INVENTION

In order to overcome the problems described hereinabove and offer animproved formulating and packaging technique, the present inventioncontemplates a two-part intraocular or tissue irrigating system. Infirst embodiment set forth in the parent application, the inventionencompass a first part which includes a stable, sterile pre-packagedacidic solution containing at least the calcium ions and magnesium ions.The second part includes a lyophilized powder containing at least thesodium bicarbonate and glutathione. The disodium hydrogen phosphate ispreferably included with the second part (powder). The potassium ionsand dextrose may be provided in either the first or second part. Whenthe first and second parts are mixed together, there is formed anextremely satisfactory irrigating solution. Preferably, the powder andsolution should be aseptically mixed to maintain the sterility thereof.

More specifically, in the proposed irrigating product, the largersolution (on the order of 500 mls) contains all the chlorides, i.e.,sodium, potassium, calcium and magnesium, in a polypropylene bottle thatis terminally steam-sterilized according to conventional processes. Thesecond or smaller part is a lyophilized powder which includes sodiumbicarbonate, disodium hydrogen phosphate, dextrose and glutathionedisulphide. The second part is sterile-filtered before being asepticallyfilled into either a glass vial or a small polypropylene bottle forlyophilization. It also has been found preferable to include thedisodium hydrogen phosphate with the sodium bicarbonate. Thus thecalcium and magnesium salts are placed in the large bottle. Both thebicarbonate and the glutathione are stabilized by the lyophilizing(freeze-drying) process.

In addition, a special technique has been developed to eliminate anybreakdown that could occur before the solution containing bicarbonateand glutathione is freeze dried. According to this improved technique,the solution containing the sodium bicarbonate is first frozen, then theglutathione is frozen onto the surface of the frozen sodium bicarbonatesolution, then both frozen components are lyophilized (freeze-dried).

The large solution is preferably placed in a 500 ml polypropylene bottleand the lyophilized powders are placed in a small 50 ml glass orpolypropylene vial. The two components are mixed aseptically through atransfer spike. One end of the spike is inserted through the stopper inthe small vial. With the bottle containing the larger amount of solutionin the upright position, the small vial is then inverted and the otherend of the spike is inserted through the stopper into the large bottle.The large bottle, being polypropylene, is then squeezed which forces asmall amount of fluid into the vial which promptly dissolves thelyophilized powder. When the polypropylene bottle is released, the fluidand powder dissolved therein will return to the large bottle. Thisprocess is repeated several times to flush all the contents of the vialinto the bottle and to thoroughly mix the contents of the twocontainers.

In an alternative embodiment, which is the subject of thiscontinuation-in-part, the present invention contemplates an intraocularor tissue irrigating system in which a powderous composition is mixedwith a conventional I.V. solution containing a portion of the sodiumsalts. The powderous composition includes a lyophilized powdercontaining at least the sodium bicarbonate and glutathione. The disodiumhydrogen phosphate, calcium salts and magnesium salts, potassium saltsand dextrose, and the remaining sodium salts are preferably includedwith the second part (powder). When the conventional I.V. solution andthe specially formulated powderous composition are mixed together, thereis formed an extremely satisfactory irrigating solution without thenecessity of having two packages on hand.

It is, therefore, an object of the present invention to provide animproved formulating and packaging technique for the manufacture ofglutathione/bicarbonate/Ringer solution type products.

Another object of the present invention is to provide an enhancedbalanced salt solution of the type described in which the sodiumbicarbonate and glutathione are packaged together in a powder form.

Still another object of the present invention is to provide alyophilized powder which can be mixed with a conventional I.V. solutionto produce the enhanced balanced salt solution.

Other objects and a fuller understanding of the invention will becomeapparent upon reading the following detailed description along with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 1A illustrate a two-part packaging system in which thecomponents of the irrigating solution of the present invention areprepackaged and stored; and

FIG. 2 is a schematic block diagram illustrative of the procedural stepsinvolved in formulating the irrigating solution of present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed generally to an improved technique forpackaging a tissue irrigating solution of the type which includesglutathione/bicarbonate/Ringer solution, whereby the components areinitially packaged in a two-component system. The composition andconcentration of the two components of the system are such that theyremain stable, even when stored for long periods of time. The twocomponents are separately sterilized, then aseptically mixed so that theultimate solution is completely sterile and available for use in surgeryduring the ensuing 24 hours. The mixed solution has been found to beextremely useful for maintaining the appropriate environment andpreventing cell damage during surgical procedures, particularlyprocedures such as intraocular surgery.

The desired irrigating solution, when mixed, preferably contains thefollowing components in the amount indicated:

    ______________________________________                                        Ingredients for Enhanced Balanced Salt Solution                                                           mg/ml                                             ______________________________________                                        Sodium chloride (NaCl)      7.14                                              Potassium chloride (KCl)    0.38                                              Calcium chloride (CaCl.sub.2.2H.sub.2 O)                                                                  0.154                                             Magnesium chloride (MgCl.sub.2.6H.sub.2 O)                                                                0.20                                              Dextrose                    0.92                                              Sodium carbonate (NaHCO.sub.3)                                                                            2.1                                               Disodium hydrogen phosphate (Na.sub.2 HPO.sub.4)                                                          0.42                                              Glutathione disulphide      0.184                                             ______________________________________                                    

As has been described above, the irrigating solution identifiedhereinabove is supplied in two parts that will be mixed by the end userimmediately prior to usage and will have usable life, when mixed, of6-24 hours. One part is a mixed salt solution shown below in Formula 1and the second part is a powder containing the components shown inFormula 2. Formula 2 dissolves readily in Formula 1 and forms a clearsolution consisting of the components in the amounts shown above. Whenpackaged and before mixing the Formula 1 and Formula 2 powder containthe following ingredients in the indicated amounts.

    ______________________________________                                        Formula 1 (500 ml Solution)                                                   Ingredients          mg/ml                                                    ______________________________________                                        Sodium chloride (NaCl)                                                                             7.14                                                     Potassium chloride (KCl)                                                                           0.38                                                     Calcium chloride (CaCl.sub.2.2H.sub.2 O)                                                            0.154                                                   Magnesium chloride (MgCl.sub.2.6H.sub.2 O)                                                         0.20                                                     Dextrose             0.92                                                     Formula 2 (Powder)                                                            Ingredients          Each Vial Contains                                       ______________________________________                                        NaHCO.sub.3          1,081 mg                                                 Na.sub.2 HPO.sub.4     216 mg                                                 Glutathione disulphide                                                                               95 mg                                                  ______________________________________                                    

Looking now at the drawing, Formula 1 is placed in the largepolypropylene container or bottle (500 ml) 10 and Formula 2 is placed inthe small container or vial (50 ml) 12. A mixing spike 14 is providedand utilized in the following manner. The mixed salt solution is carriedcontainer 10 and the lyophilized powder in container 12. One end of thespike 14 is placed through the rubber stopper 13 in vial 12. The vial 12and spike 14 are then inverted and the other end of the spike is placedthrough the rubber stopper 11 in the cap of bottle 10. The bottle 10 ispreferably formed of a resilient polypropylene material, so that when itis squeezed, a portion of the fluid is forced up into the small vial 12,where it mixes with and dissolves the powder therein. When the bottle 10is released, the fluid then flows back down through spike 14 into thebottle 10. When this process is repeated several times, the powder isfully mixed, dissolved, and transferred into the large container 10. Thesmall vial and spike are then disposed of, and the large container isready for use in the operative procedure.

In the alternative embodiment, the present invention contemplates anintraocular or tissue irrigating system for mixing with an I.V.solution. The invention includes a lyophilized powder containing atleast the sodium bicarbonate and glutathione. The disodium hydrogenphosphate, calcium salts and magnesium salts, sodium salts, potassiumsalts and dextrose are preferably included with the lyophilized powderto form a powderous composition. When the I.V. solution and powderouscomposition are mixed together, there is formed an extremelysatisfactory irrigating solution.

As has been described above, the alternative embodiment of theirrigating solution identified hereinabove is supplied in powdered formthat will be mixed by the end user with a conventional I.V. solutionimmediately prior to usage and will have usable life, when mixed, of6-24 hours. Preferably, one part is the I.V. solution shown below inFormula 1 and the second part will be the powder containing thecomponents shown in Formula 2. Formula 2 dissolves readily in Formula 1and forms a clear solution consisting of the components in the amountsshown above. When packaged and before mixing the Formula 1 and Formula 2powder contain the following ingredients in the indicated amounts,wherein the I.V. solution of the mix comprises ingredients substantiallyin the following relation:

    ______________________________________                                        Formula 1 (500 ml I.V. Solution)                                              Ingredients        mg/ml                                                      ______________________________________                                        Sodium chloride (NaCl)                                                                           4.5                                                        ______________________________________                                    

and wherein said lyophilized powder comprises ingredients substantiallyin the following relation:

    ______________________________________                                        Formula 2 (Powder)                                                            Ingredients          Each Vial Contains                                       ______________________________________                                        Sodium chloride (NaCl)                                                                             1,320 mg                                                 Potassium chloride (KCl)                                                                             190 mg                                                 Calcium chloride (CaCl.sub.2.2H.sub.2 O)                                                             77 mg                                                  Magnesium chloride (MgCl.sub.2.6H.sub.2 O)                                                           100 mg                                                 Dextrose               490 mg                                                 NaHCO.sub.3          1,152 mg                                                 Na.sub.2 HPO.sub.4     208 mg                                                 Glutathione disulphide                                                                               97 mg                                                  ______________________________________                                    

In the ensuing examples, there are explained several experiments whichwere conducted in order to determine the preferred manner forformulating the irrigating solution of the present inventions. Inpreparation for experiments 1-6, the following solutions A and B wereprepared.

    ______________________________________                                        Solution A                                                                    Ingredients          Amounts                                                  ______________________________________                                        Distilled water      10     liters                                            NaCl                 71.4   gms                                               KCl                  3.79   gms                                               CaCl.sub.2           1.54   gms                                               MgCl.sub.2           2.00   gms                                               ______________________________________                                    

Divide Solution A into four equal lots, 1A-4A, each lot equalingapproximately 2.5 liters, and adjust the pH of each lot with 1N HCl asfollows:

    ______________________________________                                                     Target                                                                              Actual                                                     ______________________________________                                        Lot 1A         pH 3.0  pH 2.9                                                 Lot 2A         pH 4.0  pH 4.1                                                 Lot 3A         pH 5.0  pH 5.5                                                 Lot 4A         pH 6.0  pH 6.9                                                 ______________________________________                                    

Fill nine 250 ml plastic bottles from each pH lot, cap and sterilize.Retain the remaining 250 ml of each lot of Solution A for furtherobservation.

    ______________________________________                                        Solution B                                                                    Ingredients          Quantities                                               ______________________________________                                        Distilled water      1      liter                                             NaHCO.sub.3          42     gms                                               Na.sub.2 HPO.sub.4   8.32   gms                                               Dextrose             18.4   gms                                               Glutathione          3.68   gms                                               ______________________________________                                    

Dissolve the Na₂ HPO₄ and the dextrose in the one liter of distilledwater. Check the pH (8.8). Add glutathione and check the pH again(7.38). Adjust the pH to 7.9-8.0 using 1 N. NaOH solution. Add NaHCO₃.Check pH (7.86). Divide the solution into three equal lots and adjustthe pH as follows:

    ______________________________________                                        Lot 1B              pH 7.9-8.0                                                Lot 2B              pH 7.7                                                    Lot 3B              pH 7.4                                                    ______________________________________                                    

Each of the above lots should be filled into 30 ml glass vials therebeing 13.25 ml in each of 18 vials of each pH. Freeze dry each vial assoon as possible after mixing.

EXPERIMENT 1

Samples of the freeze-dried Solution B were received and the followingtests were performed. First 13.1 mls of water was added to each of twovials of each of the three different types of pH samples and the pHchecked immediately and after one hour.

                  TABLE 1                                                         ______________________________________                                        Original pH   Sample No.                                                                              Reconstituted pH                                      ______________________________________                                        7.6           (1)       8.24                                                                (2)       8.23                                                  After 1 hour  (2)       8.26                                                  7.73          (1)       8.27                                                                (2)       8.28                                                  After 1 hour  (2)       8.30                                                  7.86          (1)       8.28                                                                (2)       8.28                                                  After 1 hour  (2)       8.30                                                  ______________________________________                                    

Preliminary tests excluded the pH 5 and pH 6 of Solution A as being toohigh initially. Thereafter, the pH 3 and pH 4 samples of Solution A wereused to mix with the three pH levels of freeze-dried Solution B.

                  TABLE 2                                                         ______________________________________                                        Mix           Immediate Three Hour                                            ______________________________________                                        2.9/7.86      7.68      7.91                                                  4.1/7.86      8.10      8.26                                                  2.9/7.73      7.58      7.84                                                  4.1/7.73      8.04      8.23                                                  2.9/7.6       7.47      7.69                                                  4.1/7.6       *8.26     8.32                                                  ______________________________________                                         *This is not a true result as a solution in water from Sample 1 had to be     used.                                                                    

In conclusion as to Experiment 1, it was determined that the pH ofSolution B could not be reduced below about 7.9 before freeze-drying.The HCl used to reduce the pH appears to liberate CO₂ from thebicarbonate and eventually all free CO₂ is lost on freeze-drying. Itwould, therefore, probably be necessary to have a very low pH (2.0 orless) in Solution A to counteract the buffering effect of the phosphateand the bicarbonate.

EXPERIMENT 2

A fresh batch of Solution A and Solution B were prepared, and the pH ofSolution B was adjusted to 7.89 before the NaHCO₃ was added. After theaddition of NaHCO₃, the pH of Solution B was 7.98. The pH of Solution Awas adjusted down to 2.5 by using 0.5 N HCl. When Solutions A and B weremixed in the correct proportions (10 ml to 0.5 ml), the pH of theinitial mixture was 7.3. After 24 hours, this had risen to pH 8.2 and,thus, did not meet the necessary criteria of pH 7.4.

EXPERIMENT 3

The purpose of Experiments 3 and 4 are to determine by comparison inExperiment 5 what is the best technique for freeze-drying Solution B. InExperiment 3, 18.4 gms of dextrose was dissolved in 1 liter of distilledwater. 900 ml of the distilled water/dextrose solution had dissolved init 8.3 gms of Na₂ HPO₄ and 42.0 gms of NaHCO₃ to form a Solution B 1having a pH of 8.15.

Using 12 mls of the remaining 100 mls of the dextrose solution, dissolvetherein 0.442 gms of glutathione disulphide to form Solution B-2 havinga pH of 2.63.

Pipette 11.9 mls of Solution B-1 into each of twelve 30 ml vials, capand place in a freezer. Cool Solution B-2 to about the freezing point,and when Solution B-1 is frozen and thoroughly chilled, add 1.3 mls ofSolution B-2 to each of nine vials of Solution B-1 and return all twelveimmediately to the freezer. The second layer of Solution B-2 frozealmost immediately on contact with the first layer, which was expectedand intended. Retain in the freezer one of the nine vials of thecombination solution B-1 and B-2 and one of the three vials of SolutionB-1 only. Freeze-dry the remainder for further tests in Experiment 5.

EXPERIMENT 4

Dissolve 18.4gms of dextrose in 1 liter of distilled water. Into 900 mlsof the dextrose solution, dissolve therein 42 gms of NaHCO₃ to formSolution B-1 with a pH of 8.03. Fill 11.9 mls of Solution B-1 into eachof twelve vials, stopper and freeze. To the remaining 100 mls of thedextrose solution, add 8.32 gms of Na₂ HPO₄. When completely dissolved(pH 8-9.5), transfer 12 mls to another container and add 0.442 gmsglutathione and dissolve forming a Solution B-2 at pH 7.36. CoolSolution B-2 to about the freezing point and, when Solution B-1 isfrozen and thoroughly chilled, add 1.3 mls of Solution B-2 to each ofnine vials and return all twelve immediately to the freezer. In the labexperiment, the second layer again froze almost immediately on contactwith the first layer as was intended. Retain in the freezer one of thenine vials of the combination solution B-1 and B-2 and one of threevials of Solution B-1 only. Freeze-dry the remainder for further testsin Experiment 5.

EXPERIMENT 5

The freeze-dried samples from Experiments 3 and 4 were received and thefollowing tests were performed on them. First, the four retained frozensamples were thawed and four equivalent freeze-dried samples werereconstituted with distilled water. The pH of all eight samples wasmeasured with the following results:

                  TABLE I                                                         ______________________________________                                                  Sample                                                                              Frozen(A)pH                                                                              Freeze-dried(B)pH                                  ______________________________________                                        Exp. 4, Solution 1                                                                        (1)     8.24       8.32                                           Exp. 4, Solution 1                                                                        (2)     7.99       8.23                                           & Glutathione                                                                 Exp. 5, Solution 1                                                                        (3)     8.15       8.26                                           Exp. 5, Solution 1                                                                        (4)     8.10       8.33                                           & Glutathione                                                                 & Na.sub.2 HPO.sub.4                                                          ______________________________________                                    

It was observed that Sample 4-B did not dissolve as rapidly as the othersamples, presumably because of "caking" of the phosphate in itsanhydrous state.

Next, three samples each of the freeze-dried complete solution (Samples2 and 4) were reconstituted with exactly 12 mls of distilled water andthe final pH checked.

                  TABLE II                                                        ______________________________________                                                        pH                                                                        Sample                                                                              1         2      3                                          ______________________________________                                        Exp. 4, Solution 1                                                                          (2)     8.26      8.21 8.27                                     & Glutathione                                                                 Exp. 5, Solution 1                                                                          (4)     8.28      8.25 8.27                                     & Glutathione &                                                               Na.sub.2 HPO.sub.4                                                            ______________________________________                                    

Mixture 2 went easily into solution whereas Mixture 4 took five minutesto completely dissolve.

In conclusion as to Experiment 5, in both Experiments 3 and 4, there wasan increase in the final pH after freeze-drying which indicates someslight loss of CO₂ during the process. The fact that the samples withoutglutathione showed a loss, although somewhat smaller, shows that thebicarbonate is inherently unstable--as is well known--and it willprobably be necessary to match the Solution 1 to the freeze-driedcomponent in each lot in a production environment in order to produce aconsistent pH in the final mixture. There was no marked difference inthe apparent bicarbonate stability between the two experiments. In viewof the solution difficulty with Experiment 4 material, it seemsreasonable to concentrate on the Experiment 3 approach, i.e., using theNaHCO₃ and Na₂ HPO₄ in Solution B-1 with only the glutathione inSolution B-2. This should help with any possible instability of theglutathione in an alkaline pH.

EXPERIMENT 6

The purpose of this experiment was to now determine whether a Solution Acould be formulated with a Solution B-1 from Experiment 3 successfully.Again, it should be kept in mind the purpose of the line of experiments(Exp. 1-6) is to determine whether a solution having a final pH ofapproximately 7.4 when Solution B is dissolved into it can be attainedand whether such pH will remain stable.

A 250 ml bottle of Solution A from Experiment 1 at a pH of 2.9 was used.A vial of freeze-dried Solution B (actually Solution B-1 from Experiment3) was added and the pH checked at 7.65. A small amount (0.2 mls) of 0.5N HCl was added resulting in a pH of 7.54. A further small amount (0.2ml) of 0.5 N HCl was added providing a pH of 7.4. Thereafter, 0.4 mls of0.5 N HCl was added to a bottle (265 mls) of pH 2.9 Solution A giving apH of 2.58. When a vial of Solution B (actually Solution B-1 fromExperiment 3) was added to this solution, there resulted a final mixturehaving a pH of 7.41. Four additional bottles of Solution A initiallyhaving a pH of 4.1 (Lot 2A) were similarly adjusted to pH values around2.6 with the following results when mixed with vials of Solution B fromeither Experiment 3 or Experiment 4.

                  TABLE I                                                         ______________________________________                                                       pH After                                                       Final pH of Solution 1 + vial                                                                  5 min.   1 hr.  3 hr. 24 hr.                                 ______________________________________                                        2.53 + Solution B (Exp. 3)                                                                     7.2      7.22   7.32  7.4                                    2.60 + Solution B (Exp. 3)                                                                     7.36     7.33   7.36  7.42                                   2.65 + Solution B (Exp. 4)                                                                     7.45     7.4    7.4   7.51                                   2.80 + Solution B (Exp. 4)                                                                     7.65     7.59   7.67  7.73                                   ______________________________________                                    

After 48 hours, there were obvious signs of degradation with depositsforming and in the case of the two higher pH values a strong smell of H₂S presumably from glutathione degradation. The two lower pH solutionsappeared more stable, with less deposit and no odor.

In conclusion:

1. The bicarbonate and phosphate in the first solution with glutathioneonly in the smaller second portion is the choice because it affords abetter chance of stability for the glutathione with the lower pH andthere is no problem of phosphate solubility when it is reconstituted.

2. A final pH of about 7.3 can be achieved by adjusting the chloridesolution (Solution A) to about pH 2.6. The higher pH of the finalsolution appears to be less stable and it appears preferable to hold thefinal pH to or below 7.4.

EXPERIMENT 7

A pilot batch of the enhanced balanced salt solution in accordance withthe above invention was produced to confirm the conclusion set forth inthe experiments above. A 15 liter batch of Solution A was prepared asfollows:

14 liters of WFI (distilled water which has been tested and qualifiedfor injection) were measured into a graduated container and 107.1 gms ofNaCl was dissolved therein.

1 liter of WFI had dissolved therein 22.7 gms KCl; 9.24 gms CaCl₂ ; and12.00 gms of MgCl₂.

250 mls of the potassium/calcium/magnesium solution was added to the 14liters of the NaCl solution and the volume was made up to 15 liters bythe addition of further WFI. The initial pH of Solution A was 6.03 andwas lowered by the addition of 1 N HCl as follows:

9 mls HCl pH 3.02

+4 mls HCl pH 2.80

+6 mls HCl pH 2.67

+6 mls HCl pH 2.57

At this point, and after thorough mixing, the solution was filled into250 ml plastic bottles, stoppered, capped and sterilized with DispersaBalansalt.

Solution B was prepared for freeze-drying in such a way that 10 mls ofthe B-1 solution was frozen and then 1 ml of the B-2 solution was addedon top of the surface of the B-1 solution. Solution B-1 was prepared bydissolving 22.0 gms of dextrose in 1 liter WFI. Approximately 800 mls ofthis solution was transferred and had dissolved in it 50 gms of NaHCO₃and 9.9 gms of Na₂ HPO₄. Additional amount of the dextrose WFI was addedto make up 900 mls and equally distributed throughout 30 ml vials at 10ml per vial and frozen. This made 90 samples.

90 mls of the remaining dextrose solution was transferred to a flask andin it was dissolved 4.4 gms of glutathione disulphide. This glutathionedisulphide solution was chilled to near freezing and 1 ml thereof wasadded to each of the 90 frozen 10 ml aliquots of the bicarbonatesolution. The vials were immediately returned to the freezer and theywere subsequently freeze-dried without allowing the material to thaw.Five frozen samples were retained as control samples and 85 were sentfor freeze-drying.

After freeze-drying, five vials were taken and the contents mixed witheach of the five bottles of Solution A and the pH of the mixtures weremeasured immediately and after 1, 5, 24, 48 and 72 hours, all at roomtemperature. The following results were obtained:

    ______________________________________                                        Sample  pH Value                                                              2 mm    1 Hr.    5 Hrs.  24 Hrs. 48 Hrs.                                                                             72 Hrs.                                ______________________________________                                        1    7.35   7.40     7.50  7.50    7.40  7.60                                 2    7.40   7.40     7.45  7.50    7.40  7.60                                 3    7.45   7.40     7.45  7.45    7.40  7.60                                 4    7.40   7.40     7.40  7.45    7.50  7.60                                 5    7.40   7.40     7.50  7.50    7.55  7.65                                 ______________________________________                                    

From the preliminary pH measurements, it appears that the process usedgives reproducible results and that the mixed product is at least asstable as any other glutathione/ bicarbonate/Ringer solution product onthe market.

EXPERIMENT 8

Based on the above experiments, it was further realized that a "powderonly" mix could be prepared which could subsequently be mixed with anI.V. solution to form a final solution suitable for an intraocular ortissue irrigating solution. Calculations based on the formulation of thepreferred two-part system, yielded the following results for a powderouscomposition containing potassium salts, calcium salts, magnesium salts,a portion of the sodium salts along with a lyophilized mixture of sodiumbicarbonate, disodium hydrogen phosphate, a glutathione substantially asdescribed heretofore suitable for mixing with a standard 500 ml 4.5 wt %sodium chloride I.V. solution, wherein the 1.V. solution of the mixcomprises ingredients substantially in the following relation:

    ______________________________________                                        Formula 1 (500 ml I.V. Solution)                                              Ingredients        mg/ml                                                      ______________________________________                                        Sodium chloride (NaCl)                                                                           4.5                                                        ______________________________________                                    

and wherein said lyophilized powder comprises ingredients substantiallyin the following relation:

    ______________________________________                                        Formula 2 (Powder)                                                            Ingredients          Each Vial Contains                                       ______________________________________                                        Sodium chloride (NaCl)                                                                             1,320 mg                                                 Potassium chloride (KCl)                                                                             190 mg                                                 Calcium chloride (CaCl.sub.2.2H.sub.2 O)                                                             77 mg                                                  Magnesium chloride (MgCl.sub.2.6H.sub.2 O)                                                           100 mg                                                 Dextrose               490 mg                                                 NaHCO.sub.3          1,152 mg                                                 Na.sub.2 HPO.sub.4     208 mg                                                 Glutathione disulphide                                                                               97 mg                                                  ______________________________________                                    

While preferred embodiments of the present invention have been describedin detail here and above, it is apparent that various changes andmodifications might be made without departing from the scope of theinvention which is set forth in the accompanying claims. For example,other I.V. solutions, such as Ringer's Injection or Lactated Ringer'sInjection could be chosen and an appropriate lyophilized powder producedwhich would result in an equivalent final solution.

I claim:
 1. A powderous composition for subsequent mixture with aconventional I.V. solution containing therapeutically effective amountsof sodium salts to form a tissue irrigating solution, said powderouscomposition comprising:a. a lyophilized powder containing sodiumbicarbonate and glutathione; b. calcium salts, magnesium salts,potassium salts, dextrose, being added to said lyophilized powder, saidlyophilized powder additionally including amounts of sodium salts wheresaid I.V. solution does not contain sufficient sodium salts as requiredfor said tissue irrigating solution; c. whereby said lyophilized powderexhibits the characteristics of extended shelf life and when mixed withsaid conventional I.V. solution forms a solution for irrigating bodytissues during surgery.
 2. The powderous composition according to claim1 wherein said lyophilized powder further comprises disodium hydrogenphosphate.
 3. The powderous composition according to claim 1 whereinsaid lyophilized powder is packaged in a polypropylene bottle.
 4. Atissue irrigating product comprising:a. a lyophilized powder containingsodium bicarbonate and glutathione; b. calcium salts, magnesium salts,potassium salts, and dextrose being added to said lyophilized powder; c.an I.V. solution containing sodium salts; d. said lyophilized powderadditionally including amounts of sodium salts where said I.V. solutiondoes not contain sufficient sodium salts as required for said tissueirrigating solution; e. means for aseptically intermixing saidlyophilized powder with said I.V. solution; f. said I.V. solution andlyophilized powder, when mixed together, forming a solution forirrigating body tissues during surgery.
 5. The irrigating productaccording to claim 4 wherein said lyophilized powder further comprisesdisodium hydrogen phosphate.
 6. The irrigating product according toclaim 4 wherein said I.V. solution is pre-sterilized prior to mixing. 7.The irrigating product according to claim 4 wherein said lyophilizedpowder is packaged in a polypropylene bottle and there is furtherincluded a double-ended mixing spike.
 8. The irrigating productaccording to claim 5 wherein, when said I.V. solution and lyophilizedpowder are mixed, the resulting solution comprises ingredientssubstantially in the following relation:

    ______________________________________                                        Ingredients for Enhanced Balanced Salt Solution                                                           mg/ml                                             ______________________________________                                        Sodium chloride             7.14                                              Potassium chloride (KCl)    0.38                                              Calcium chloride (CaCl.sub.2.2H.sub.2 O)                                                                  0.154                                             Magnesium chloride (MgCl.sub.2.6H.sub.2 O)                                                                0.20                                              Dextrose                    0.92                                              Sodium carbonate (NaHCO.sub.3)                                                                            2.1                                               Disodium hydrogen phosphate (Na.sub.2 HPO.sub.4)                                                          0.42                                              Glutathione disulphide      0.184                                             ______________________________________                                    


9. The irrigating product according to claim 5 wherein said I.V.solution comprises ingredients substantially in the following relation:

    ______________________________________                                        Formula 1 (500 ml I.V. Solution)                                              Ingredients        mg/ml                                                      ______________________________________                                        Sodium chloride (NaCl)                                                                           4.5                                                        ______________________________________                                    

and wherein said lyophilized powder comprises ingredients substantiallyin the following relation:

    ______________________________________                                        Formula 2 (Powder)                                                            Ingredients          Each Vial Contains                                       ______________________________________                                        Sodium chloride (NaCl)                                                                             1,320 mg                                                 Potassium chloride (KCl)                                                                             190 mg                                                 Calcium chloride (CaCl.sub.2.2H.sub.2 O)                                                             77 mg                                                  Magnesium chloride (MgCl.sub.2.6H.sub.2 O)                                                           100 mg                                                 Dextrose               490 mg                                                 NaHCO.sub.3          1,152 mg                                                 Na.sub.2 HPO.sub.4     208 mg                                                 Glutathione disulphide                                                                               97 mg                                                  ______________________________________                                    


10. The irrigating product according to claim 9 wherein the pH of saidfinal solution is no greater than 7.8.
 11. A method for preparing aprepackaged tissue irrigating product for subsequent mixture with aconventional I.V. solution to form a tissue irrigating solutioncomprising the steps of:a. preparing an aqueous solution havingdissolved therein at least sodium bicarbonate and glutathione; b.lyophilizing the solution of step (a); c. packaging the lyophilizedpowder of step (b) along with a powderous mixture of calcium salts,magnesium salts, potassium salts, dextrose, and additional amounts ofsodium salt as may be necessary to provide the required amounts in saidtissue irrigating solution which is ultimately formed.
 12. The methodaccording to claim 11, wherein the aqueous solution of step (a)additionally contains disodium hydrogen phosphate.
 13. The methodaccording to claim 12 wherein step (a) includes forming a first solutionof said sodium bicarbonate and disodium hydrogen phosphate and a secondsolution containing said glutathione.
 14. The method according to claim13 wherein step (b) includes freezing said first solution, thenintroducing said glutathione second solution onto the frozen surface ofthe first solution whereby the second glutathione solution freezes, thenfreeze-drying the resulting combination of the frozen first solution andfrozen second solution.